Magnesium is a versatile material suitable for diverse applications across a variety of sectors. Although you can use magnesium alloys to create high-quality components with excellent corrosion resistance, magnesium is highly flammable in CNC machining operations.
Therefore, it is helpful to take the necessary precautions to process magnesium safely. Taking care when CNC machining with magnesium will help minimize safety risks.
Risks of Magnesium Processing
Machining magnesium alloys presents risks that must be treated with care. You may know some of the risks of CNC machining magnesium.
Fire risk
The fine chips and dust produced when machining magnesium alloys are highly flammable and can easily cause a fire. Fire can result from excessive heat or small sparks created during processing.
Tool wear
CNC machining of magnesium results in faster tool wear than other metallic materials due to its relatively soft and abrasive properties. This significantly reduces machining efficiency and increases tool replacement costs.
Heat generation
Magnesium has low thermal conductivity, resulting in high heat concentration in the cutting zone. Furthermore, high cutting temperature leads to reduced tool life, workpiece deformation and tool wear.
Surface texture deformation
Magnesium alloys are often prone to burr formation and deformation due to machining. Therefore, without suitable machining strategies and tool selection, it is difficult to achieve the desired high surface quality.
Important Tips for Safely Processing Magnesium
If you take the necessary precautions, precision CNC machining is a versatile method for safely machining magnesium. Below you will find tips for processing magnesium safely.
Keep your tools in good condition
Using sharp cutting tools for your magnesium CNC machining will help reduce hazards as dull tools can cause extreme heat. As a result, chips from the CNC machining process can catch fire.
However, carbide tipped tools maintain their hardness and do not tend to produce sparks when machining magnesium at higher temperatures.
Avoid narrow clearance angles
It is advisable to avoid narrow clearance angles when machining magnesium alloys, even though they can be machined at higher speeds without compromising part quality. When machining with narrow clearance angles, longer, more continuous chips are created in which the rotating cutting tool can easily get stuck. This can result in high heat levels and the flammability of magnesium alloys can pose a serious fire risk.
Make batch chips
Examine the size and type of chips produced during the magnesium CNC machining process. As a general rule, program your CNC machines to produce well-broken or discontinuous chips. Uninterrupted chips help efficiently dissipate heat from the cutting tool and workpiece surface, reducing the risk of ignition.
Program your cutting tool to use a small rake angle to produce well-broken chips. Then use low feed speeds and a medium to high cutting speed. However, you can also obtain interrupted chips with large cutting depths.
Avoid water-based sodas
CNC machining of magnesium will likely generate excessive heat if your project does not use small rake angles, low feed rates, or moderate cutting speeds. Therefore, you must use mineral oil coolant during machining. These coolants reduce the risk of fire and explosion and improve the surface quality of machined magnesium parts.
However, it is not advisable to use water-based coolants when machining magnesium. These water-based refrigerants can react with magnesium to form highly flammable hydrogen gas.
For chips, use an explosion-proof vacuum cleaner
Magnesium chips created during processing remain a hazard even after the processing parameters required for the production of magnesium chips have been respected. Modern CNC shops now use vacuum systems and explosion-proof extraction systems to safely remove magnesium chips and dust from CNC machines.
Never put out magnesium fires with water
If a fire accident caused by magnesium occurs during processing, it is not advisable to put it out with water. This is not an ideal option as using water would only worsen the severity of the fire. Therefore, you can use Class D dry extinguishers to quickly contain magnesium fire. Likewise, dry sand is an easy alternative when trying to put out small fires.
Why Choose Magnesium for CNC Machining?
Since CNC machining magnesium involves risks, the question arises as to why use it. That's a legitimate question. However, magnesium is ideal for CNC machining if you follow safety guidelines. Magnesium is a lightweight structural metal with excellent surface finish and machinability. There are typical reasons why you should choose magnesium for CNC machining.
Excellent machinability
Magnesium is much easier to cut and shape using CNC machining processes because the material has excellent machinability properties. Magnesium alloys have lower cutting forces, which reduces wear on the cutting tool.
Complex geometries
As magnesium alloys are very easy to machine, they are perfect for machining special parts with complex geometries. Additionally, CNC magnesium machining provides magnesium components with precise, complex characteristics that meet the rigorous requirements of modern engineering projects.
With CNC machining, there is no room for error in producing magnesium parts with microscopic precision when the process is based on programmed instructions. Furthermore, the machining center of multi-axis CNC machines has multiple spindles that can machine magnesium alloys from different angles according to requirements.
Recyclability
Magnesium can be recycled because its alloys are environmentally friendly. Magnesium is therefore an ideal material for sustainable manufacturing processes. CNC machining processes also produce magnesium waste that can be recycled.
Selection of tools for machining magnesium alloys
Choosing a CNC cutting tool is a crucial factor when machining magnesium alloys. It is important to use sharp tools to avoid excessive heat generation during machining operations. Below you will find typical tools used in magnesium machining.
High Speed Steel Tools
High speed steel cutters are made from hardened alloy steel, making them ideal for machining applications with lower requirements and low to medium production volumes. HSS tools are inexpensive, readily available, and provide the low cutting speed needed to cut magnesium materials.
Carbide Tools
Carbide end mills, reamers and drills are widely used magnesium CNC machining tools because of their excellent heat resistance and high hardness. These carbide tools are remarkably wear and heat resistant, making them perfect for demanding magnesium alloy machining applications.
Coated Carbide Tools
Cutting tools with special coatings such as titanium aluminum nitride (TiAlN) or titanium nitride (TiN). The thin coating on these tools increases their wear resistance and reduces the formation of built-up edges when machining magnesium.
Furthermore, these coated tools exhibit impressive thermal stability, allowing them to perform well despite the high temperatures generated during magnesium machining.
Polycrystalline Diamond Tools
These tools offer excellent wear resistance and are ideal for machining high-quality surfaces on parts made from magnesium. Machinists often use these tools to machine magnesium alloys because they are effective in machining hard materials or magnesium alloys with high abrasiveness.
Various CNC Machining Processes for Magnesium
Using CNC machining methods, magnesium can be efficiently cut to produce various parts for different applications.
CNC Drilling
CNC drilling is a versatile method of drilling holes in magnesium parts using milling cutters or rotary bits. Most applications require precise drilling and CNC machines provide the high precision needed to create complex hole patterns.
CNC Milling
CNC milling is one of the most popular CNC machining techniques for magnesium materials. This method uses a rotating cutting tool to create the desired shape when milling magnesium. CNC milling is extremely effective and suitable for machining simple and complex geometries.
CNC turning
CNC turning involves cutting material from a rotating magnesium alloy held in a chuck. This process is perfect for machining cylindrical shapes such as pins, shafts and threaded parts.
Laser cut
This is another common CNC machining process for magnesium. High-performance lasers are used to achieve precise cuts in magnesium sheets or plates. Laser cutting is ideal for producing thin, complex parts quickly and efficiently.
Touch
Threading is a reliable method machinists use to create internal threads in machined magnesium components. CNC machining helps automate this method. This allows you to obtain accurate dimensions and thread pitches.
Don't Worry About Getting Magnesium Machining Parts from WayKen
Concluding
Magnesium machining creates lightweight components with high strength, impact resistance and good dimensional stability. However, there are several magnesium CNC machining processes to produce different parts for different applications.
Although magnesium has excellent machinability properties and CNC machining is very versatile, machining magnesium is associated with certain hazards. Therefore, it is useful to understand how magnesium alloys are machined to ensure safety during machining operations.
Common questions
Which magnesium alloy is best for machining?
The best magnesium alloys commonly used in machining are AZ91 and AZ31. However, AZ91 features a higher Knoop Hardness (HK) of 76.2, while AZ31 offers 51.1 HK.
What are the disadvantages of machining magnesium alloys?
Despite the extensive benefits offered by machining magnesium, its relatively limited availability, lack of corrosion resistance and lower density represent significant limitations.
What is magnesium commonly used for?
Magnesium alloys are versatile materials commonly used to manufacture lightweight components such as camera housings, medical devices and electronics such as phones and laptops. Additionally, magnesium alloys are used in the construction of certain high-performance vehicles.
Can I weld magnesium?
You can easily weld magnesium alloys using arc and resistance welding processes as well as oxyfuel gas welding technology.
